1. Field of the Invention
The present invention relates to a lightning current detection sensor for detecting a current flowing in a lightning strike and a simulation current of the current flowing in the lightning strike.
2. Description of the Related Art
Aircraft are required to take all possible measures to ensure safety in a lightning strike. When a main wing of an aircraft is struck by lightning and a large current flows, the current partially or, in some cases, entirely flows through connecting portions between wing surface panels on a surface of the wing. If a value of the current exceeds a limit value of a passage allowable current at each connecting portion, electric discharge referred to as an electric arc (or thermal spark) occurs. This is considered to be a phenomenon in which an instantaneous large current flows through the connecting portions between wing surface panels mainly made of a conductive material to cause a sudden increase in temperature, and as a result, melting and vaporization of a member causes electric discharge in surrounding atmosphere. When this phenomenon occurs, melts referred to as hot particles are scattered from a melting portion in many cases.
Generally, an inner space of a wing also functions as a fuel tank, and in the lighting strike, it is necessary to prevent occurrence of the electric arc or seal the arc to prevent electric discharge of the arc that has occurred and hot particles scattered thereby from contacting flammable fuel vapor.
Thus, the applicant has made various studies and proposals to prevent an electric arc. In the process of the studies, the need has arisen to evaluate how a current flows in a lightning strike to check effectiveness of measures against a lightning strike.
To evaluate how a current flows in a lightning strike, as shown in FIG. 7, a magnetic field M that is produced in an object 100 through which a current A flows by a lightning strike is detected by a magnetic detection sensor 1.
A general magnetic detection sensor includes, for example, a sensor using a magnetic detection coil with an annular band-like conductor (for example, see Japanese Patent Laid-Open No. 2006-343196), or a sensor using a thin film flux gate (for example, see National Publication of International Patent Application No. 2009-535616), but these sensors are not suitable for evaluating how a current flows in a lightning strike.
Specifically, in a lightning strike, as shown in FIG. 8, a high current of several tens to 200 kA and a high voltage of 40 to 50 kV flow in a short time, and noise contamination cannot be avoided. As a magnetic detection sensor for detecting a lightning current, a sensor resistant to high current and high voltage needs to be used, but the techniques described in Japanese Patent Laid-Open No. 2006-343196 and National Publication of International Patent Application No. 2009-535616 are intended for detecting a minute magnetic field and does not assume use for detecting a lightning current.
When a high current and a high voltage flow, noise contamination occurs due to capacitative coupling with a surrounding electric field, and this makes it difficult to detect only a magnetic field produced by a current change. Thus, as a magnetic detection sensor 1 resistant to high current and high voltage, for example, as shown in FIG. 9, a shield loop antenna 5 in which a looped core wire 2 is passed through a copper pipe 3 and an insulating material 4 is filled between the copper pipe 3 and the core wire 2 is conventionally generally used. Such a shield loop antenna 5 can avoid influence by an electric field because the copper pipe 3 and the insulating material 4 form a shield against an electric field.